1. Field of the Invention
The present invention relates to a radio controlled time piece and a method for controlling same, and more particularly to a radio controlled time piece and control method which limits electrical power consumption, and also maintains the precise time information at all times.
2. Background Art
A time piece configured to receive a radio wave signal including time information and automatically correct the time to the precise time has already been practically developed. Additionally, radio wave signals (hereinafter referred to as standard radio wave signals) which include standard time information for use in a radio wave signal controlled watch are transmitted, for example, in a number of countries, such as Japan, US, Germany, UK, and China and the like.
The frequency and transmitted data format of the above noted radio wave signals, which include time information, differ.
A radio controlled time piece, such as noted above, in general can be classified as a time piece of the type in which forced reception operation is performed by a user, or a time piece of the type that performs a time-programmed operation. In a forced reception operation, the user, as necessary, operates a prescribed external input means, such as a switch, a button, a stem or the like, so as to forcibly receive a standard radio wave signal that includes the above-noted time information. A time piece of the type that performs the time-programmed operation uses a set program of conditions that is pre-determined, based on the timekeeping information value of a timekeeping means reaching a prescribed value, whereby automatic time correction is performed by receiving the prescribed standard radio wave signal at a prescribed receiving time. There are radio controlled time pieces which use each of these receiving methods individually, and radio controlled time pieces which make use of both of the above-noted receiving methods. In a radio controlled time piece of this type, where the user of the radio controlled time piece moves from a prescribed area (or country) to another area (or country), or even within one and the same prescribed area (or country), and the user of the time piece is in a location (for example, behind a building or in an underground room) where it is not possible for the standard radio to reach the watch, neither of the above-noted receiving operation methods will enable reception of the standard radio wave signal that includes the prescribed information. In this type of case, where, as noted above, both of the receiving methods are provided together, and in the case in which the time-programmed receiving method only is provided, the operation of time-programmed reception operation is performed repeatedly using the time-programmed receiving operation method. In the case in which both receiving operation methods are provided, when the user executes a forced-reception operation, operation occurs using, of course, this forced reception method. However, in the case of time-programmed reception method, because execution is always performed when a predetermined time has come, more attention is required.
However, the operation of receiving a standard radio wave signal that includes time information in a radio controlled time piece is one that consumes a considerable amount of electrical power, so that in such a time-programmed reception operation mode, execution of the receiving operations is made over a long period of time in accordance with the prescribed reception mode, regardless of the fact that reception is not possible. Unwanted power consumption occurs because the receiving operation is repeated. As a result, there is an increase in the overall power consumption, so that not only is the battery life shortened, but also there is a problem of an increase in cost for battery replacement. In a radio controlled time piece of the re-chargeable type, in the condition in which the charge is not so high, there is wasteful power consumption for the purpose of repeating the receiving operation, regardless of the fact that reception is not possible. As a result, there is an increase in the overall power consumed, thereby resulting in a problem not only with receiving operation, but also a problem of the time piece ultimately stopping.
In the case in which the user of a radio controlled time piece that includes time information moves to a region or country in which it is not possible to use the standard radio wave signal that had been received up to that point, or if the user is in the shadow of a building or in an underground room, the time piece is placed in a condition in which it is not possible at all to perform time correction using a time-programmed reception. But in the case in which the configuration of the radio controlled time piece is such that it can receive a standard radio wave signal, including time information utilizing the forced reception operation, even in the condition in which it is not possible to receive using time-programmed reception, when the user comes up to an outside area of a building from an underground room, by executing forced reception operation for a standard radio wave signal, it is possible to successfully receive the standard radio wave by performing the forced reception operation.
However, even if a radio controlled time piece is provided with forced reception operation mode, because the standard radio wave signal that includes time information is normally set to one type only, for example in the case of movement from a prescribed region (or country) to another region (or country), even if there is no problem for the case in which there is a receivable station that broadcasts a standard radio wave signal that can be received within that region or country, in a different case, because time correction is not possible, there is a loss of usability of the radio controlled time piece.
On the other hand in Japanese un-examined patent publication No. (KOKAI) 2003-270370, there is a time data receiving apparatus having a timekeeping means, a radio wave signal receiving means capable of receiving a plurality of radio wave signals which have different frequencies and include time data, a receiving frequency switching means for switching the frequency of radio wave signals that are received by the radio wave signal receiving means, a controlling means for controlling the switching of the frequency by the receiving frequency switching means, and a time correction means for correcting the current time data, based on the time data included in a radio wave signal that is received by the radio wave signal receiving means. This further has a success/failure judging means for judging the success or failure of reception of a radio wave signal by the radio wave signal receiving means, and a storage means for storing the frequency. Further, the above-noted control means performs control of the above-noted receiving frequency switching means so that the frequency of the radio wave signal received by the radio wave signal receiving means is switched to a frequency that is stored in the storage means. Also, in the case in which the success/failure judgment means makes a judgment of failure, the control means performs control so that the receiving frequency switching means is switched from the current frequency to another frequency. In the case in which the success/failure judging means returns a judgment of success, control is performed so that the frequency of a radio wave signal received by the radio wave signal receiving means is stored into the storage means.
In the Japanese un-examined patent publication No. (KOKAI) 2002-296374, there is a time information acquisition method, whereby a plurality of time information signals having differing frequencies are received and the receiving condition of each of the time information signals is detected. A specification is made of one time information signal for time information acquisition from the above-noted time information signals, based on these receiving conditions, and time information being acquired from that specified time information signal.
In addition, in Japanese un-examined patent publication No. (KOKAI) 2003-75561, there is an automatically corrected time piece that performs time correction by receiving a plurality of standard radio wave signals having differing frequencies and including a standard time signal and performing the correction based on these standard time signals. The time piece comprises a receiving section which can set a plurality of resonance frequencies in accordance with a control signal. The receiving section further enables the demodulation of the received standard radio wave received with the resonance frequency and thus sets an output standard time signal. Also included is a control circuit which outputs to the receiving section a control signal to set a resonance frequency being different from the above-mentioned set resonance frequency for the case when it is not possible for the receiving section to demodulate the standard time signal from the standard radio wave with a set resonance frequency within a predetermined limited period, and perform the time correction operation based upon the standard time signal.
In Japanese Patent No. 3454269, there is a radio controlled time piece indicated which has a timekeeping means, a current time display means for displaying the current time in accordance with timekeeping, a receiving means for receiving a radio wave signal that includes time information, a receiving power supply control means for causing periodic operation of a receiving power supply means that drives the receiving means, and a current time correction means for correcting the current time of the timekeeping means based on the time information received by the receiving means. Additionally, in this watch, the receiving power supply control means has an elapsed-time detection means for determining the amount of time elapsed from the time of the previous reception of the radio wave, a schedule information setting means for setting the schedule information that establishes the operating time interval when periodic operation of the receiving power supply means is to be performed, and a power supply means control means for controlling the operation of the receiving power supply means, based on the above-noted schedule information. The above-noted schedule information setting means is configured so as to switch the above-noted schedule information when the elapsed time reaches a set time or above, and to schedule information where the time interval for operation is longer than an initially set value.